Avalanche Forecast
Issued: Dec 7th, 2020 4:23PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Deep Persistent Slabs.
Grant Statham,
A short but intense storm will run for 24-hrs overnight Monday and end by Tuesday afternoon. More snow to the west, less to the east. Could see 30-40 west of the divide with huge wind. All this snow will bond poorly to old snow surface.
Summary
Weather Forecast
A strong SW flow over the area will bring (possibly) significant snow overnight Monday and through the day on Tuesday. By Tuesday afternoon it will all be over. Expect a windy one early Tuesday (up to 120 km/hr), but these should taper through the day. Temperatures will remain moderate (0 to -8), then begin to cool as the skies clear for Wednesday.
Snowpack Summary
Welcome the Dec 8 layer, it should be a good one that we will all get to know. A mix of large surface hoar, sun crust, facets and old windslab from the clear skies will get buried overnight on Monday, pushed by strong to extreme winds. This will result in a short period of instability as the new snow will not bond well to all of these old grains.
Avalanche Summary
No avalanches reported on Monday, perhaps that least day of the long spell of stable conditions.
Confidence
Forecast snowfall amounts are uncertain on Tuesday
Problems
Wind Slabs
This all depends on how much snow comes. Models show a maximum of 65 (unlikely) to 30 or less (expected). Strong winds are certain, so Tuesday is a day to spend in the forest and see how the new snow sticks to the Dec 8 layer just being buried.
- The new snow will require several days to settle and stabilize.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Deep Persistent Slabs
The Nov 5 crust has facets above and below it, and exists up to 2500m on shady aspects and higher on solar aspects. This problem has been unreactive recently but we expect it will reawaken with enough load. Stay off big terrain through this storm.
- Be aware of thin areas that may propogate to deeper instabilites.
- Pay attention to overhead hazards like cornices which could trigger the deep persistent slab.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Dec 8th, 2020 4:00PM
